Electronic devices, and specifically semiconductor devices and memory devices, are becoming increasingly more complex. Accordingly, circuitry area or space, also termed “real estate,” in electronic devices is becoming more and more limited. In an effort to provide more circuitry on a single semiconductor chip without increasing the size, as well as in an effort to reduce the size of other semiconductor chip, the circuitry has become increasingly smaller and a greater number of circuits are formed on a single chip. For example, memory devices have reduced from microscale devices and circuits to nanoscale devices and circuits. Nanoscale is conventionally defined as referring to circuits and pitches less than 100 nanometers.
An example of a memory device having memory cells formed on the nanoscale includes magnetic shift registers, conventionally referred to as “racetrack memory.” An example of racetrack memory is described in U.S. Pat. No. 6,834,005 to Parkin, assigned to International Business Machines Corporation (IBM). FIG. 10 of the drawings of the present application is a perspective view illustrating a prior art embodiment of an array of racetrack memory. Racetrack memory may include an array of nanoscale wires or tracks 1010 made of a ferromagnetic material. Each track 1010 may include a plurality of magnetic shift registers 1020 connected to each other in series. Each magnetic shift register 1020 includes a writing device 1030 and a reading device 1040 associated therewith. Because of the small size of the tracks 1010, the array of tracks 1010 may be arranged very close together in a memory device. While nanoscale memory cells are desirable for providing increased storage capacity in a limited real estate, conventional supporting circuitry (e.g., charge pumps, decode and addressing circuits, sense amplifiers, I/O circuits, etc. (not shown)) of a memory device may not need to be formed on such a small scale and, indeed, may be more efficiently and economically formed on a microscale as opposed to a nanoscale.